Mixing device

ABSTRACT

The mixing device is used for mixing multicomponent materials or for homogenizing compositions which are contained in a cartridge (10) which is closed by a piston (15) having a passage opening (19). The latter is primarily closed by the shaft (22) of a mixing member (20). Said shaft (22) may be coupled to a rod (23). By a drive or by manual operation, the rod (23) may be rotated and moved axially at the same time. While the piston (15) stays, where it is, the mixing member (20) is moved through the cartridge (10). Upon termination of the mixing operation, the mixing member (20) is locked at the piston (15) by a holding member (32) in order to unscrew the rod (23) from the mixing member. Subsequently, the cartridge may be inserted into a squeezing tool in which the piston (15) is advanced for squeezing out the composition.

The invention relates to a mixing device for mixing and homogenizingpasty or flowable compositions.

Prior to being processed, pasty or flowable compositions often require amixing or homogenizing operation. This is particularly necessary if theyconsist of more than one component such as synthetic resin and hardenerwhich are combined directly prior to the processing. Such masses areused for inst. as sealing agents or adhesives or as plastic impressivematerial.

There have been known mixing devices containing a number of componentsseparately accommodated in various compartments. Prior to the blendingoperation, the compartments are interconnected or a partition wallbetween the compartments is destroyed or removed thus enabling thecomponents to come into contact. Thereafter, the masses present in acartridge are treated with a mixing member comprising a rod extendingout of the cartridge and adapted to be manually moved axially and to berotated. Subsequently, the mass contained in the cartridge may besqueezed out by moving out thereof a piston.

The production of the known mixing means is involved and expensive andthe mixing effect is mostly unsatisfactory. If several components arecontained in one common cartridge, it is always suited for a specificquantitative ratio of the two components only. In other words, suchcartridges are useful, but simply for a definite material which requiresa specific mixing ratio. Added thereto, the component available in a lowamount, is often inflammable. In such a case, the total cartridge mustbe stored according to fire-protection rules by observing certain safetyregulations although only a relatively low percentage of the cartridgecontent is inflammable.

According to the instant invention, the mixing member is connectedthrough the piston to the rod required for its operation. For the mixingoperation, the mixing member is reciprocated in axial direction of thecartridge, and it may be rotated simultaneously about its longitudinalaxis. Upon termination of the mixing operation, the mixing member isplaced against the piston end wall, and the rod is removed from themixing member which is retained by the piston. Upon the separation, themixing member together with the piston forms one sole unit which may beused for squeezing the mixture out of the cartridge. To this effect, usemay be made of customary squeezers which normally serve for squeezingsealing substances out of cartridges.

It is a particular advantage that the usual tubular catridges may beused without any modification. The mixing member which, during themixing operation, is movable separately from the piston, is connected tothe latter upon termination of the mixing phase, whereby the mixingmember closes the passage opening of the piston thus obtaining a tightend wall of said piston. Upon separation of the rod from the mixingmember, the latter forms, so to speak, part of the piston, and, duringthe following squeezing operation, it is not moved independently. In away, the piston is completed by the mixing member fixed thereto. Duringmixing, the piston serves as an element for closing the cartridge andfor guiding and sealing the rod. In the delivery state, the mixingmember may be also joined to the piston, unless the rod is connected tothe mixing member. For the mixing operation, the rod is connected to themixing member which is retained by the piston. By an axial advance ofthe rod, the connection between the mixing member and the piston iscleared thus enabling the mixing member to freely operate, while thepassage opening of the piston is sealed against the rod thus preventingthe mass from escaping from the cartridge along the rod.

It is preferable to provide the mixing member with a hollow shaft whichis sealingly received by a sleeve projecting rearwardly from the frontpiston surface. The outer diameter of the shaft is equal to that of therod connectable therewith. The connection between rod and hollow shaftis preferably realised by threads, in particular by a multiple thread.

The mixing member comprises a flat disk with openings and blades adaptedto swing out of the disk plane and, preferably, the mutually confrontedor averted edges of two blades are hinge-connected with the disk. Theblades which, responsive to the axial travel motion of the mixingmember, are swivelled through the pasty composition, are always set insuch a way that, upon rotation of the mixing member in one sense ofrotation, one of the two mentioned blades helically cuts its paththrough the composition, while the other blade offers an increased flowresistance. As a result, it is ensured that the mixing member does nothelically cut the composition against a low resistance only, but theagitative effect on the mass caused by at least one of the blades isquite considerable.

The mixing apparatus of the invention may be used for homogenizing oneof the compositions contained in the cartridge, prior to being used. Insuch a case, the total mass is contained in the cartridge. It is alsopossible to mix several components. In such a case, the componentconstituing the major portion of the mixture is already contained in thecartridge, while the other component is added later. The smallercomponent amount may be fed later through the spout provided in thecartridge end wall and later used for sequeezing. Of course, said spoutshould be closed by a cap during the mixing operation.

One embodiment of the invention will be now explained hereunder in moredetail with reference to the drawings in which:

FIG. 1 is a longitudinal section of the mixing apparatus,

FIG. 2 is a section along line 2--2 of FIG. 1,

FIG. 3 is a section along line 3--3 of FIG. 1 and

FIG. 4 is a perspective view of the mixing member.

The illustrated mixing apparatus comprises a customary cartridge 10which consist of a molded part, of metal or of paper material, formed asan elongated, cylindrical tube closed at its one end by a wall 11, whilethe opposite end 12 is open. The end wall 11 is provided with a spout 13having an external thread through which the mass may be expelled out ofthe cartridge. In the illustrated condition, spout 13 is closed by adetachable wall 14.

The cartridge 10 accommodates a piston 15 whose cylindricalcircumferential wall 16 sealingly rests against the inner cartridgewall. From the plane front piston surface 16a forming the end wall,there project rearwardly resp. outwardly the peripheral wall 16, anannular reinforcing wall 17, and a sleeve 18, the peripheral wall 16exceeding towards the end the reinforcing wall 17 and the sleeve 18.Only the front ends of all of said three walls 16, 17, 18 are connectedto the piston wall 16a, while the rear ends project freely. Sleeve 18encloses the passage opening 19 which axially traverses piston 15.

Upon the insertion of piston 15 into the cartridge 10 through the openend 12, the latter is deformed such as to bring about a stop 12aretaining the piston in the cartridge. The cartridge is filled throughthe open spout 13 whose wall 14 is removed.

The passage opening 19 of piston 15 is closed by the mixing member 20comprising an interrupted disk 21 flatly resting against the piston wall16 and whose outer diameter is somewhat inferior to that of piston 15.From the rear side of disk 21, a hollow shaft 22 extends to the rear,said shaft 22 filling completely and tightly the cross section of sleeve19. Inside said shaft 22, there is an internal thread into which thethread piece 23a at the front end of rod 23 is screwed. The threads ofsleeve 18 and of thread piece 23a are of the double type. Due to such athread design, by rotating the rod 23, the meshing of the threads may bedetected more easily and the threads may be tightened more quickly. Theshaft 22 does not extend as far as to the rear end of sleeve 18. Intosaid end, there extends the main part of rod 23 which is behind thethread piece 23a and whose diameter is equal to that of shaft 22.

The disk 21 comprises a number of openings 24, 25, 26, among whichopenings 24 and 25 contain blades 27 or 28 which, by film hinges 29 and30 are connected integrally with the disk 21. As for blades 27 arrangedoppositely, the film hinges 29 are disposed at the radial edges beingforwardly directed clockwise, while the film hinges 30 at blades 28 aredisposed at the radial edge being forwardly directed anticlockwise. Ifthe mixing member 20 is axially moved in the cartridge 10, all of thefour blades 27, 28 are folded outwardly counter to the travel direction.If the mixing member is rotated at the same time, only two of saidblades point to the sense of rotation, while the remaining bladesindicate to the counterdirection. Thus, a helical cutting of the bladesinto the pasty composition is avoided and, by the blades pointing incounterdirection, an agitating effect on the mass is ensured.

The openings 26 are simple holes. The periphery of disk 21 is providedwith uniformly distributed recesses 31 designed as peripheral slotsradially open outwardly. Each recess 31 may coact with a holding member32 of piston 15, the holding member 32 being a shoulder forwardlyprojecting from the piston surface 16a and dipping into a recess 31 whendisk 21 rests against the piston surface 16a. In such a case, theholding member 32 forms a resistance to rotation inhibiting a rotationof disk 21 relative to piston 15. By this means, the rod 23 may beunscrewed from the mixing member 20, while the latter is retainedagainst rotation by the holding member 32 of the piston 15, whoseperipheral wall 16 frictionally supports itself inside the cartridge 10,whereby the torsional resistance is so high that the piston 15 is notturned when the rod 23 rotates within the cartridge 10. The shoulder maybe saw-tooth shaped so that the mixing member 20 is blocked relative tothe piston 15 but only in one sense of rotation, while it may rotate inthe other direction. If bar 23 is rotated in the release direction,mixing member 20 should be prevented from rotating by the holding member32.

The mixing device is supplied in the condition shown in FIG. 1, with theexception that shaft 23 is not screwed in place, while the compositionto be squeezed out or one component of said mass may be inside cartridge10.

In operation of the mixing device, wall 14 of spout 13 may be cut offfor the introduction of an additional component into the cartridge 10.Subsequently, spout 13 is closed by a (non-illustrated) screw cap. Now,one only needs to screw rod 23 into shaft 22 of the mixing member.Thereafter, rod 23 may be connected to a driving unit, e.g. a portabledrill to rotate the rod and the mixing member 20 at the same time.During such a rotation, the threads of thread pieces 23a and shaft 22are tightened. As a result, rod 23 may be moved axially throughcartridge 10, while all cartridge areas are subjected to the mixingeffect. As for blades 27, 28 of the mixing member 20, they areautomatically adjusted such that, with respect to the axial movement,they point to the rear.

Upon termination of the mixing or homogenizing operation, the mixingmember 20 is withdrawn until it rests against the piston surface 16.Now, rod 23 is turned counter to its preceding sense of rotation inorder to release the thread engagement with the mixing member 20 which,at the same time finds its support by the holding member 32, while shaft22 seals the passage opening 19 of piston 15. Upon removal of rod 23,the cartridge 10 may be mounted into a usual squeezing tool, such as aspray gun in order to squeeze the cartridge content out of the spout 13.

The mixing member 20 is provided with an axial attachment 33 projectingforwardly and being adapted to penetrate, during mixing, into theinterior of the spout 13, in order to also displace the mass presentthere. The cross section of the attachment 33 is out of round; in theinstant embodiment, it consists of three star-shaped ribs. When thematerial is squeezed out of the cartridge, the mass present in the spout13 is expelled by said attachment 33.

What is claimed is:
 1. Mixing device for mixing or homogenizing pasty or flowable compositions comprisinga tubular cartridge (10), having at its one end a front wall (11), while its other end (12) is open, a mixing member (20) accommodated in the cartridge (10) and connected to a rod (23) extending out of the open cartridge end, and a piston (15) for squeezing out the cartridge content, characterized in that the piston (15) has an axial passage opening (19) for the rod (23) or for a shaft (22) projecting from the mixing member (23), the rod (23) is detachably connected to the mixing member (20), the piston (15) includes a holding member (32), and said holding member (32) defines means for retaining the mixing member (20) against rotation as said mixing member (20) is separated from the rod (23).
 2. Mixing device as set forth in claim 1, characterized in that the piston (15) includes a sleeve (18) projecting to the rear from the piston surface (16a) and forming a seat for a hollow shaft (22) provided at the mixing member (20), the shaft (22) containing a coupling means for the connection with rod (23).
 3. Mixing device as set forth in claim 2, characterized in that the coupling means is a thread.
 4. Mixing device as set forth in claim 3, characterized in that the thread is at least a double thread.
 5. Mixing device as set forth in claim 1, characterized in that the holding member (32) is a projection engaging as an antirotation protection a recess (31) of the mixing member (20).
 6. Mixing device as set forth in claim 5, characterized in that the projection is saw tooth-shaped to retain the mixing member (20) only in release direction of the rod (23) relative to the piston (15).
 7. Mixing device as set forth in claim 1, characterized in that the mixing member (20) is a disk (21) provided with openings (24,25,26), among which some openings (24,25) contain blades (27,28) adapted to swing out of the disk plane.
 8. Mixing device as set forth in claim 7, characterized in that at least two blades (27,28) are hinge-connected to the disk (21) at their mutually confronted or averted radial edges.
 9. Mixing device as set forth in claim 1, characterized in that the mixing member (20) includes an axial attachment (33) having an out-of-round profile which penetrates a squeezing spout (13) at the end wall (11) of the cartridge (10).
 10. Mixing device as set forth in claim 1, characterized in that a stop (12a) at the rear end (12) of the cartridge (10) is provided to avoid the escape of piston (15). 